Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 170830A: Fermi GBM observation
  2. Konus-Wind observation of GRB 170827B
  3. Konus-Wind observation of GRB 170826A
  4. GRB 170830A: Astrosat CZTI detection
  5. LIGO/Virgo G299232: GRAWITA Asiago optical observations
  6. LIGO/Virgo G299232: continued WHT observations of the field of SwiftJ014008.5+343403.6
  7. LIGO/Virgo G298936: PIRATE observations
  8. LIGO/Virgo G299232 ANTARES search (2)
  9. LIGO/Virgo G298048: GMRT Follow-up of SSS17a at 1.4 GHz
  10. Konus-Wind observation of GRB 170826B
  11. LIGO/Virgo G299232: GRAWITA Campo Imperatore optical observations
  12. LIGO/Virgo G298048: Discovery of X-ray emission from SSS17a in NGC4993
  13. GRB 170830A: iTelescope optical observations
  14. LIGO/Virgo G298048: European VLBI Network (EVN) upper limit on 5 GHz compact emission from SSS17a
  15. LIGO/Virgo G299232: SVOM/2.16-m Optical Telescope Observations of Swift UVOT Transient
  16. GRB 170830A: MAXI/GSC detection
  17. LIGO/Virgo G298048: OVRO 40m telescope follow-up
  18. LIGO/Virgo G299232: HAWC follow-up
  19. LIGO/Virgo G299232: Further Swift/UVOT Observations of Optical Transient SwiftJ014008.5+343403.6
  20. LIGO/Virgo G299232 : RATIR Optical and NIR Observations of Swift UVOT source
  21. LIGO/Virgo G299232: WHT non-detection u-band optical transient
  22. LIGO/Virgo G299232: Liverpool Telescope observations
  23. LIGO/Virgo G299232: observations of the optical Transient Discovered by Swift/UVOT
  24. IPN Triangulation of GRB 170826B
  25. LIGO/Virgo G299232: PIRATE observations of MASTER OT J033744.97+723159.0
  26. LIGO/Virgo G298936: Updated localization from parameter estimation on LIGO and Virgo data
  27. LIGO/Virgo G298048: ALMA upper limits on 98 GHz emission from SSS17a
  28. LIGO/Virgo G299232/PGWB170825.55: early MASTER observations of the Swift UVOT source position
  29. LIGO/Virgo G296853: PIRATE observations
  30. LIGO/Virgo G298048: ALMA observations
  31. LIGO/Virgo G298048: Konus-Wind observations
  32. LIGO/Virgo G299232: GRAWITA Asiago/Copernico Telescope observations
  33. LIGO/Virgo G298048: Zadko Telescope 7 day observations of the OT candidate SSS17a/DLT17ck
  34. GRB170827A: Further GROND follow-up observations
  35. LIGO/Virgo G299232: COATLI Observations of MASTER OT J033744.97+723159.0
  36. LIGO/Virgo G299232 : MAXI/GSC observations
  37. LIGO/Virgo G298048: Further ATCA follow-up of SSS17a in NGC 4993
  38. GRB 170826B: Insight-HXMT detection
  39. LIGO/Virgo G299232: Continued observation of the transient near NGC 1343
  40. LIGO/Virgo G299232: WHT spectrum of MASTER OT J033744.97+723159.0
  41. LIGO/Virgo G299232/PGWB170825.55: MASTER OT J033744.97+723159.0 inside 25m isophota of the NGC1343 galaxy is reddening
  42. IPN Triangulation of GRB 170827B (short)
  43. IPN Triangulation of GRB 170826A (short)
  44. LIGO/Virgo G299232: Optical Transient Discovery by Swift/UVOT
  45. LIGO/Virgo G298936: HAWC follow-up
  46. LIGO/Virgo G299232 TZAC/TAROT observations
  47. GRB 170827A: Swift-XRT refined Analysis
  48. GROND observations of GRB170827A
  49. GRB 170827A: ePESSTO NTT afterglow candidate
  50. GRB 170823A: TAROT Calern observatory optical observations
  51. LIGO/Virgo G299232: OVRO-LWA simultaneous low frequency radio observations of localization region
  52. LIGO/Virgo G299232: LOFAR follow-up
  53. GRB 170827A, Swift-BAT refined analysis
  54. LIGO/Virgo G299232: Transient near NGC 1343 has a somewhat blue r-i color
  55. GRB 170827A: Swift/UVOT Upper Limits
  56. GRB 170827A: REM optical/NIR observations
  57. LIGO/Virgo G299232/PGWB170825.55: MASTER OTJ033744.97+723159.0 off set from NGC1343 galaxy
  58. LIGO/Virgo G299232/PGWB170825.55: MASTER Global-Net OT inside NGC1343 discovery
  59. GRB 170827A: Swift detection of a burst
  60. GRB 170826B: Fermi GBM detection
  61. LIGO/Virgo G299232: CALET Observations
  62. GRB 170826A: Fermi GBM detection
  63. LIGO/Virgo G298936: Astrosat CZTI upper limits
  64. LIGO/Virgo G299232: XRT Rank 2 source is not real
  65. LIGO/Virgo G299232: Astrosat CZTI upper limits
  66. LIGO/VIRGO G299232: Fermi GBM Observations
  67. LIGO/Virgo G299232 : Fermi-LAT search for high-energy gamma-ray counterpart
  68. LIGO/Virgo G298389: HAWC follow-up
  69. LIGO/Virgo G298048: uGMRT Follow-up of SSS17a at 400 MHz and 1.4 GHz
  70. LIGO/Virgo G299232: Nearby Galaxies in the Localization Volume
  71. LIGO/Virgo G298936: CALET Observations
  72. GRB 170820A CALET Gamma-Ray Burst Monitor detection
  73. LIGO/Virgo G299232: Swift/BAT data search
  74. LIGO/VIRGO G298048: INAF VST-ESO PARANAL observations of NGC4993
  75. GRB 170822A: AstroSat CZTI detection
  76. LIGO/Virgo G299232: AGILE GRID observations
  77. LIGO/Virgo G299232: AGILE MCAL detection of a short gamma-ray candidate
  78. LIGO/Virgo G299232: INTEGRAL search for a prompt gamma-ray counterpart
  79. LIGO/Virgo G299232: COINCIDENT IceCube neutrino observation UPDATE
  80. LIGO/Virgo G296853: VLT observations by GLGW Hunters
  81. LIGO/Virgo G299232 ANTARES search
  82. LIGO/Virgo G297595: INTEGRAL pointed follow-up observations
  83. LIGO/Virgo G299232: FOUND COINCIDENT IceCube neutrino observation
  84. LIGO/Virgo G299232: Identification of a GW Compact Binary Coalescence Candidate
  85. LIGO/Virgo G297595: Gemini and VLT observations by GLGW Hunters
  86. LIGO/Virgo G298936: Liverpool Telescope Spectoscopy of GWFUNC-17ure
  87. LIGO/Virgo G298936 TAROT/TZAC observations
  88. GRB 170825A: AGILE/MCAL Detection
  89. LIGO/Virgo G298936 : MAXI/GSC observations
  90. LIGO/Virgo G298048: MASTER Global-Net early optical observations and the Possible KiloNova SSS17a in NGC 4993 photometry and merging rate
  91. LIGO/Virgo G298048: Pierre Auger Observatory neutrino follow-up
  92. LIGO/Virgo G298048: Subaru HSC z-band imaging of the OT candidate SSS17a
  93. LIGO/Virgo G298048: Near-infrared fading from Gemini-South
  94. LIGO/Virgo G298048: HAWC follow-up
  95. LIGO/Virgo G298048: Gemini-South Imaging and Spectroscopy
  96. LIGO/Virgo G298048: MUSE Integral Field Observations
  97. LIGO/Virgo G298048: LWA radio observations
  98. Konus-Wind observation of GRB 170822A
  99. GRB 170823A: Swift-BAT refined analysis
  100. LIGO/VIRGO G298048: AAT/AAO spectroscopic observations of the GW counterpart candidate SSS17a/DLT17ck

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov